Paraventricular stimulation with glutamate elicits bradycardia and pituitary responses
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- D. N. Darlington
- Department of Physiology, University of California, San Francisco94143.
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- M. Miyamoto
- Department of Physiology, University of California, San Francisco94143.
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- L. C. Keil
- Department of Physiology, University of California, San Francisco94143.
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- M. F. Dallman
- Department of Physiology, University of California, San Francisco94143.
書誌事項
- 公開日
- 1989-01-01
- DOI
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- 10.1152/ajpregu.1989.256.1.r112
- 公開者
- American Physiological Society
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説明
<jats:p> The excitatory neurotransmitter, L-glutamate (0.5 M, pH 7.4), or the organic acid, acetate (0.5 M, pH 7.4), was microinjected (50 nl over 2 min) directly into the paraventricular nuclei (PVN) of pentobarbital sodium-anesthetized rats while arterial blood pressure and heart rate and plasma adrenocorticotropic hormone (ACTH), vasopressin, and oxytocin were measured. Activation of PVN neurons with L-glutamate led to increases in plasma ACTH, vasopressin, and oxytocin and a profound bradycardia (approximately 80 beats/min) with little change in arterial blood pressure. Microinjection of acetate had no effect on the above variables. The decrease in heart rate was shown to be dependent on the concentration of glutamate injected and the volume of injectate. The bradycardia was mediated through the autonomic nervous system because ganglionic blockade (pentolinium tartrate) eliminated the response; atropine and propranolol severely attenuated the bradycardia. The bradycardia was greatest when L-glutamate was microinjected into the caudal PVN. Injections into the rostral PVN or into nuclei surrounding the PVN led to small or nonsignificant decreases in heart rate. Focal electric stimulation (2-50 microA) of the PVN also led to decreases in heart rate and arterial blood pressure. These data suggest that activation of PVN neurons leads to the release of ACTH, vasopressin, and oxytocin from the pituitary and a bradycardia that is mediated by the autonomic nervous system. </jats:p>
収録刊行物
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- American Journal of Physiology-Regulatory, Integrative and Comparative Physiology
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American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256 (1), R112-R119, 1989-01-01
American Physiological Society